Brachytherapy involves the delivery of radiation dose via radioactive seeds within or adjacent to the tumour using either percutaneous insertion of needle applicators or insertion of intracavity applicator(s). A range of different applicators have been developed for several different tumour sites, including prostate, cervical, vaginal, rectal, esophagus, and lung. The applicator insertion is typically performed using ultrasound guidance or simply palpating the anatomy and guiding the applicator to the correct position.
Following the insertion of the applicator, x-ray images are typically acquired to determine the location of the applicator relative to the anatomy. However, increasingly, MR has been used in brachytherapy for imaging applicator placement and for treatment planning purposes. This move to MR has led to the development of MR-compatible applicators and accessories. The typical workflow for including MR in the brachytherapy process involves insertion of the applicators, moving the patient to the MR suite, and then once again moving the patient to another location for treatment.
Once the applicator is in place, the patient is moved to a radiation shielded bunker for high dose rate (HDR) treatment delivery, or a typical patient hospital room for pulsed dose rate (PDR) or low dose rate (LDR) treatments. For HDR therapies, the applicators in the patient are hooked up to long transfer tubes that connect to a remote after-loader device. The after-loader device provides a set of connections for the transfer tubes, through which the after-loader can move radioactive seeds (typically Co-60 or Ir-192) along the transfer tubes and into the applicators in the patient. The radioactive seeds stop at certain points along the applicator for predefined lengths of time to create a conformal dose distribution pattern. Once complete, the radioactive material is brought back along the transfer tube into the after-loader.
The main drawback of the MR inclusion in HDR brachytherapy today is that it involves moving the patient between the location of applicator insertion, MR imaging and treatment bunker. Some approaches have integrated the insertion of needles within the MR, using sophisticated tabletop designs or MR-compatible robotic systems. However, these approaches still require that the patient be transported between the MR and treatment bunker.
In U.S. Pat. No. 8,513,946 (Petropoulos) issued Aug. 20, 2013 filed May 14, 2010 assigned to IMRIS there is disclosed a “Movable table for Magnetic Resonance Imaging”, which includes an embodiment of the invention with a pelvic region cut-out to provide access for pelvic procedures.
In U.S. Pat. No. 8,295,906 (Saunders) issued Oct. 23, 2012 and originally published Feb. 25, 2010 assigned to IMRIS there is disclosed the integration of MRI with radiation therapy.
U.S. Pat. No. 7,908,690 (Luginbuhl) issued Mar. 22, 2011 assigned to Sentinelle Medical there is disclosed an MR table top for MR-guided interventions called “Supine patient support for medical imaging.
The disclosures of the above patents are hereby incorporated herein by reference.